Searched around so sorry if this has been posted. Seems there are a lot of people with lighting problems that would seem to point to the alternator. Sometimes it gets fixed, sometimes not. I had an '01 model that did it and it went away after replacing the alternator and battery BUT the positive battery lug/insert was corroded out. I just picked up an '02 last week that pulsed every time I drove it up until three days ago.

First thing I did was replace the alternator and battery. The battery was dated 2007 so it was a matter of time before it went out anyway. This did nothing. So then I started going through the body grounds and found that every one of them under the hood are painted over from the factory. They did use grounding ring terminals with teeth that are supposed to bite through crud to help connection but on my car these did not appear sufficient to cut through the paint. This creates insufficient contact area because contact then only happens through the threads of the bolt. I know everyone always says "CHECK YOUR GROUNDS" but like I said I haven't seen this problem addressed and you would never find a problem with this using a DMM because you only need a hair of contact to read continuity. Where is shows up is once you start pulling current across it. The poor path is an increased load and requires more current from the supply. Under many conditions the voltage drop this causes may be sensed by the system and alternator charge is ramped up to compensate eventually burning up the alternator, or at least causing a fluctuating overshoot/undershoot from the PCM charge command.

Here are some pics. I used a Dremel with drum sander to clean the paint off all of the contact points and also clean the terminals. After doing this and reinstalling I haven't had light pulses for the past three days whereas before it was every time I drove the car.



Main body ground from battery negative. This is what Early Cuyler would call "sorrier 'n' hell". That's what, an 8AWG and 12 AWG cable landed there with an actualy contact point of....well....about nothing. I can tell you that from the little I've seen this is not what is considered normal practice for the industry...typically the stud they use has the nut installed on it when the body is painted, then the nut is removed so bare metal is exposed.





Driver's side ground strap, bad pic I know. The ground strap does not have teeth, but it was installed directly to the frame and the ground wire installed with it which did have teeth was on top. Nothing but maybe one thread of the sheet metal screw actually conducting between the frame and engine.





Grounds on radiator support. Headlights maybe?

 

Excellent post!!!

This is a project for next weekend.

No - they say to put on a bigger alternator! It's like squishing a cockroach with a sledge hammer. It will work, but there will be other consequences of the action.

 

What battery and alternator did you replace with?
Interesting that what you did there stopped the flickering.
I replaced my alternator with a 150a powermaster and it totally fixed the problem.
Maybe if I did what you did my stock alternator would still get it done? Hmmm.

 

I used a Duralast (Delphi) remanufactured alt and Duralast Gold battery. They didn't have new ones in stock and I didn't want to wait. The one I pulled out was a Delphi but I don't know if it was original or not. I've not returned the core yet so I may try it out this weekend.

Gotta figure at least on the body ground what good is it to use a cable with 8 sq mm cross section if your contact point is less than half that. Once it gets hot the resistance just goes up. All the bad grounds are costing amperage once everything's loaded and hot so getting rid of them may pull the system draw back down below the stock alt's rated output.

 

As corrosion and gunk buildup increases resistance even further, you start to see a lot of the charging issues that people complain about as these cars get older. People forget that these cars came off the assembly line without any pulsing/flickering/etc. issues, even with the stock amperage alternator. Cleaning up these points is a good idea, and should result in improvements even beyond how the system functioned when the car was new.

Having said that, since many of these cars have a bunch of miles on them now, simply cleaning up ground points probably won't be enough to solve every issue - alternators do wear out over time. A fresh, good quality alternator and good, clean ground contacts should be enough to get any LS1 with stock/near stock accessories to charge properly.

 

Moving to electronics...

 

I think RPM WS6 hit on the corrosion = resistance issue well. That will cause charging issues as there should be a voltage drop.


I've been kicking around this issue in my mind for a while and have been puzzled because I don't see a voltage drop with the pulsating.

Capacitors and/or voltage regulators smooth out pulsating in circuits - so I thought a bad electronics in the alternator could be the culprit, but the problem doesn't always go away with new alternators. (It didn't in my case.)

I'm wondering of the corrosion on the grounds is adding inductance or capacitance to the circuits, which would then cause the surges? I just did some reading and see that corrosion has capacitance and/or inductance properties but my head started hurting really really bad. (Its been a long time since I was in to this stuff.) Cleaning my grounds is probably going to be easier than reading about the finer points of rust, capacitance, and inductance...

 

My alt caught on fire one night on way to work.. Was actually a good thing, fixed flickering when I put in a truck alternator and for years car would throw random codes..since new alt, no flicker, no codes, 14+ volts even at stoplight with ac, stereo booming. Anyone with stereo putting out some power..get a alternator.

 

Surprised no ones said it.

While you're doing all the work and sanding contacts, Do the Big 3!!
Pretty much get 4awg wire, and install it WITH your stock wires for alt pos, engine ground and frame ground.
It will help a decent bit if you have a sub amp.

If you have a High output alt like I do, Use something bigger then 4awg, Mine is done in 2/0 lol. But I have a 300 amp tenney alternator

And please, Don't buy into the capacitor scam. They dont do anything! Buy a decent battery for your trunk, it'll help 100x more then a cap, and about the same price.

 

I am also experiencing lights flickering problem and my volt gauge is dancing around- a lot! I'm going to try cleaning the grounds before I replace the alternator and save myself $120+

Everything SSellers said makes perfect sense to me and I can't believe how crappy the factory grounds are!

 

Any updates from any of you guys as to this being a long term fix?

 

Still fine on mine five months later.